(1) Field of the Invention
The present invention relates to a thermoplastic resin composition having excellent heat resistance, transparency and light resistance. More particularly, the present invention relates to a thermoplastic methacrylimide group-containing resin composition having improved weatherability.
(2) Description of the Related Art
It is known that a methacrylimide group-containing polymer is a thermoplastic resin having a high heat distortion temperature and a high transparency (see Japanese Examined Patent Publication No. 60-38404).
However, the methacrylimide group-containing polymer has a poor resistance to sunbeams, wind and rain, and heat and cold. Namely, the weatherability of the methacrylimide group-containing polymer is not satisfactory, and reduction of the transparency and degradation of the appearance are often caused. Accordingly, the poor weatherability is a very important problem in practical use of this polymer.
Attempts have been made to improve the weatherability of the methacrylimide group-containing polymer by incorporating various ultraviolet absorbers such as benzophenone type ultraviolet absorbers and benzotriazole type ultraviolet absorbers. However, even if such an ultraviolet absorber is used, a methacrylimide group-containing polymer comparable to a methyl methacrylate resin, which is a transparent resin having a highest weatherability, cannot be obtained.